In the world of credit ratings, it's generally acknowledged that the most overrated securities are structured products, while the most underrated securities are municipal bonds. (You have no idea how nice it is to be able to use the words "overrated" and "underrated" literally.)

As the credibility of the ratings agencies falls, then, the least-affected borrowers, in terms of the price they have to pay to access the market, are likely to be municipalities. And that seems to be exactly what's happening. Historically, US municipalities have paid $2 billion per year to bond insurers, in order to get their issues a triple-A credit rating and appeal to the type of investors who only want AAA-rated debt ...